In a liquid crystal display device, an alignment film is one of most important components, and is configured for making liquid crystal molecules in contact with the alignment film having a certain orientation. The alignment film generally is formed of a polyimide (PI) material. In order that the alignment film has alignment ability, an alignment treatment needs to be performed on the alignment film.
The alignment treatment for example is a rubbing alignment, i.e., a surface of the alignment film is rubbed with a rubbing roller with fine piles, thereby forming lots of tiny grooves on the surface of the alignment film and the lots of tiny grooves serving as an alignment structure. However, during the rubbing alignment process, there are lots of problems; for example, a pollutant may be brought into the alignment film, the alignment film may be easily damaged and so on.